This invention relates to an N port feed waveguide device which supports multiple signals having multiple frequencies and polarities. More specifically, this invention relates to an N port feed waveguide device that separates signals by polarity and when coupled with discrete filters, separates signals by frequency and is configured so that it can be produced in a single casting process.
As technology advances, an increasing number of reflector antenna applications, including satellite and other antenna type applications, require complex multi-port assemblies to support the multiple polarities and multiple frequency band signals that are used in such assemblies. Typically, these assemblies that support such polarities and frequencies are referred to as waveguides. The complexity increases and certain difficulties arise when in addition to the input port in which the signals are all received, these systems also further require signals having multiple polarities to be transmitted and signals having multiple polarities to be received.
In response to such needs, assemblies have been developed to process such signals; however, these conventional assemblies have a number of associated deficiencies. For example, the time and complexity for manufacturing conventional N port feed devices are considerable and thus, the overall cost of the manufacturing process significantly increases as the complexity and number of waveguide components increase.
N port feed devices, such as a diplexer, are typically connected between a feed horn and transmitter and receiver hardware that is used to frequency select the signals that are uplinked and downlinked. A diplexer, such as a co-polarized diplexer, uses waveguide filters and a waveguide junction to separate the co-polarized uplink and downlink signals presented to the co-polarized diplexer in a first waveguide and to feed separate transmitter and receiver hardware in a second waveguide. In order to select appropriate, desired downlink and uplink frequencies, the diplexer may have a number of filters formed therewith permitting tuning of these frequencies. For example, a bandpass filter and a high pass filter may be provided as part of the diplexer to provide frequency tuning. The tuning is accomplished by turning multiple bandpass tuning screws and multiple high pass tuning screws. Thus, this type of device suffers from the disadvantage that it requires multiple tuning filters, including tuning screws, to be provided and then manipulated in order tune the diplexer to appropriate frequencies so that acceptable performance is achieved.
FIG. 1 is an illustration of a conventional N port feed device 10. In this case, the N port feed device 10 is a Ku band four port feed wide band. As is clearly visible in FIG. 1, the N port feed device 10 has a complex structure due to its complex geometric design. Because of the complex geometric design, the manufacture and assembly of the N port feed device 10 is likewise complex and requires a number of manufacturing and assembly steps. This adds considerable cost to the manufacturing of the N port feed device 10. The geometric design of the N port feed device 10 is complex because it includes a number of curved sections and the different waveguides each have different sections of varying cross-sectional dimensions. This prevents the N port feed device 10 from being manufactured using a single die cast manufacturing process as one or more casting tools, i.e., mandrels, are unable to be slidably removed from the cast structure surrounding the tools due to the geometry of the design. Typically, the N port feed device 10 is formed as different components and then is assembled together. For example, the individual components can be separately manufactured using a die cast process and then connected to one another using suitable techniques, such as fasteners or a welding operation, etc.
FIG. 2 is a side view of another conventional N port feed device 20. In this instance, N port feed device 20 is a three port feed device (N=3) which is formed of a first part 22 and a second part 24. The first and second parts 22, 24 are formed separately using standard manufacturing processes, such as die casting, and then the two parts 22, 24 are secured to one another using a plurality of fasteners 26, e.g., bolts. This device 20 is also of conventional design as a number of separate components are first fabricated and then assembled at a later time.
Accordingly, it is desirable to provide an N port feed device that separates signals by polarity and when coupled with discrete filters separates signals by frequency, wherein the N port feed device is simple and inexpensive to manufacture and does not require tuning.
According to one embodiment of the present invention, a waveguide assembly of an integral cast construction is provided and includes a plurality of integral waveguide members. A first waveguide member is provided and configured to carry a first signal having first and second polarities. A second waveguide member is co-axially aligned with the first waveguide member and configured to carry a second signal having at least one polarity. The second waveguide member communicates with the first waveguide member through a first coupling aperture.
The device also includes third and fourth waveguide members that are in communication with an interior of the first waveguide member. The waveguide members are arranged so that the first signal is separated as it is carried within first waveguide member such that the first polarity is separated and carried within the third waveguide member and the second polarity is separated and carried within the fourth waveguide member.
According to one aspect, each of the first, second, third and fourth waveguide members has a cross-section that decreases along an axis containing the waveguide in a direction from a distal end to a proximal end. The device functions as an N port feed device and acts to separate polarized input signals that are received, i.e., through a feed horn, and channeled into the first waveguide member. In one embodiment, the second waveguide member is a transmit port that is attached to a radio or the like. The transmit port receives transmit signals that travel therein and through the first aperture and into the first waveguide member. The third and fourth waveguide members act as side receive ports that are each configured to receive only a signal of one polarity, while the other polarity is cut off.
The present N port feed configuration is designed so that it is non-tunable and is able to be manufactured using a single die casting operation to thereby produce the integral cast construction due to its shape. The more complex geometric configurations of conventional devices prevent a die casting operation from being used. The use of a single die casting operation results in reduced manufacturing costs and reduced manufacturing time.